A research study has been designed to: 1) detect directly, by means of spin label measurements, membrane lesions produced from in vivo exposure of alveolar macrophages to pollutant atmospheres--both oxidant and reducing; 2) obtain experimental evidence that these lesions are, or are not, associated with activity of membrane-bound enzymes and with phagocytic and respiratory capacity of the alveolar macrophage; 3) relate dose-dependence of observed induced membrane lesions with response of intracellular systems--specifically lysosomal enzymes, a cytoplasmic enzyme, cAMP, and RNA/DNA synthesis; 4) assess the effects of the same in vivo exposures upon selected lung systems which will either exert a pharmacological effect upon the macrophage membrane (such as cAMP), or provide an altered substrate for phagocytosis by the alveolar macrophage (i.e., the lung surfactant); and 5) evaluate the effects of the metabolic and functional state of the alveolar macrophage itself (i.e., actively phagocytic or resting) upon production of lesions, impairment of function, and particularly upon surrounding lung tissue.